Application of a smartphone based spectrophotometer for rapid in-field determination of nitrite and chlorine in environmental water samples

In this paper, a low cost and portable smartphone-based spectrophotometer with the purpose of measuring trace levels of two important anions, chlorine and nitrite ions in water samples, is introduced. This home-made spectrophotometer is made of Plexiglas, equipped with two LEDs as a light source, and a piece of DVD is acted as light dispersing element. Battery of smartphone was used as its power supply and spectral analysis was performed by a free software downloadable from Google Playstore. By using this lightweight spectrophotometer, various environmental samples were analyzed for their NO2- and Cl2 content in field. Good detection limits of 5.00 × 10-2 mg L-1 and 8.60 × 10-3 mg L-1 were obtained for chlorine and nitrite, respectively. The linear range for chlorine was 1.00-4.00 mg L-1 and this range for nitrite was 0.05-1.20 mg L-1. Reproducibility as relative standard deviation for both chlorine and nitrite was better than 8.75%. In order to investigate validity of data, results were compared to standard methods of measuring chlorine and nitrite, using both spectrophotometry and commercial kits which showed no difference between results obtained. This very simple to use and inexpensive device can be used many times, so can be considered as a low-cost alternative to the detection device of commercial kits.